Bumpers: why not?
 

I was very suprised by the amount of teams without bumpers and the number of ramming penalties incured by those teams. Why would any team now want bumpers? If you have a ball grabber then just put the bumers on the back and hit people backwards.

1549 had bumpers and we did lots of hard hitting never getting a ramming penalty. Bumpers also allow you to add 15 pounds to the robot. Extra C in F=ukC is always welcome!

Re: Bumpers: why not?
 

Our bot didn't need bumpers to protect itself and we could not afford andextra 15 pounds added. we ended up at 119.9 pounds

Re: Bumpers: why not?
 

the 15 pounds do not go toward your 120, they are in addition to the limit of 120. This means you can legally weigh 135 with the bumpers on.

Re: Bumpers: why not?
 

You get an additional 15 lbs just for the bumpers (that is, 15 lbs on top of the 120 you're allowed for the robot).

<R10> The weight of any bumper assemblies included on the robot that are in compliance with Rule <R35> is excluded from the robot weight limit specified in Rule <R09>, up to a maximum of 15 pounds.

<R35> Goes into more detail about bumper specifications, if you're interested.

In any case, 857 doesn't have bumpers simply because we didn't have enough time to make them. That might change at the Milwaukee regional, though.

Re: Bumpers: why not?
 

We had trouble with the ramp with the bumpers on...and the only place on the robot that recieved damage was in the ball intake area where we can't put a bumper anyways.

Re: Bumpers: why not?
 

Sorry I didn't know that 15 pounds were added onto the 120, but still our bot is really solid and doesn't need bumbers. Also we didn't have time to make them even if we wanted them

Re: Bumpers: why not?
 

The bumpers were a huge problem for us on the ramp. They allowed us to get up but we could not get back down. The first time we tried we fell and damaged a critical part of our robot. We only had to remove them from the back though, so we still have protection on our sides.

Re: Bumpers: why not?
 

I determined early on that bumpers would not match the aesthetic sensibilities of the rest of our design, thus, we have no bumpers. :)

Re: Bumpers: why not?
 

A very valid and simple reason to not have bumpers:

They easily go into the lower goals beyond 3". They will result in your team being disqualified in the seeding rounds or your entire alliance being DQed in the elimination rounds.

Even if you are pushed in by an opposing robot - you will be DQed.

Bumpered beware!

-Mr. Van
Coach, 599

Re: Bumpers: why not?
 

Good point. I never thought about the corner goal penalty.

Re: Bumpers: why not?
 

This is where I see fault with FIRST and not the team. We would have designed bumpers within this weight limit that wouldn't have entered the goal but because of the standard bumper configuration, we are forced to make them a certain way. Generally we avoid those areas anywho.

Re: Bumpers: why not?
 

it cant be that hard to add an offset at the top of you robot to keep you from entering the goal.
Like 2 of those spring doorstops. they don't weight anything and they'd work just fine.

Re: Bumpers: why not?
 

When your robot is right at 120 lbs (us) you cant add anything. Plus that thing sticking out can interact with other robots infringing on the contact rules for touching robots ouside the bumperzone.

Re: Bumpers: why not?
 

Just curious: Why would you ever need to go down the ramp during a match? I cannot think of a possible reason - but then again, I'm not very imaginative. Any enlightenment would be received gratefully.

Don

Re: Bumpers: why not?
 

if you get pushed up the opponets ramp, then you need to go down so they dont get the points, and so youcan continue playing.

Re: Bumpers: why not?
 

There are several robots that are designed to shoot from atop the ramp. They must get off the ramp to not score points for their opponents and to collect more balls.

Re: Bumpers: why not?
 

or they could just build some thing that dips down to touch the floor . . .

Re: Bumpers: why not?
 

we had this problem since we didnt have a bumper on our front where we have the ball loader/corner goal scorer and we almost had problems but then we cut the bumpers back so they dont extend past the end of the chassis problem=solved

btw ramming is still a penality regardless of bumpers or not bumpers may allow you to increase you speed doing it but not much we got a penality for ramming with our unprotected side during autonomous but they still would've given us the penality even if we had done it backward where we have bumpers---- just a warning

Re: Bumpers: why not?
 

We had to remove our "front" bumpers for this reason. :(


Bill Pease
Aces High Team 176
2006 UTC New England Champions with 177 and 1124
2006 BAE Granite State Finalists with 319 and 562
2005 UTC New England Engineering Inspiration Award

Re: Bumpers: why not?
 

Yes, your bumpers can extend past that limit. the solution? we got the idea from a few other teams to put a guard up so that our robot would stop before its bumpers could get too far into the goal.
The 'guard' was just a peice of metal placed at each corner of the robot, just inside the bumpers. this allowed for us to stop before we reached the sensor, and therefore wouldnt get a penalty.

Re: Bumpers: why not?
 

Well, we had bumpers, and on the wood ramp we had no problems.

When we got to competition however, the extra 1/4 inch of diamond plate caused us not to be able to go up the ramp.

Re: Bumpers: why not?
 

I was thinking about this the other day coming from a physics perspective.

One of the most important and fundamental equations in physics is F = ma (Force equals mass times acceleration). Now think about this equation while imagining an impact between two robots.

In a collision, a robot with bumpers will have a smaller acceleration upon impact than a robot without them. Because acceleration is the change in velocity divided by the change in time, the acceleration is small because a bumper gives the robot more time to stop. The smaller the acceleration, the smaller the resulting force. In the same way, there is smaller acceleration when a car comes to a gradual stop, as opposed to when a car crashes head on into a tree. There is more force exerted on the person in the car that crashes into the tree, than there is on the person who comes to a gradual stop.

The force imparted by a bumpered robot is smaller than a non-bumpered robot. This fact can be taken into account when deciding whether or not to use bumpers. If you are planning on being an offensive shooter-bot, the use of bumpers would help you because it would make the force of impacts smaller. This would make it harder for your opponents to knock you out of scoring position. However, if you are planning on playing defensively, bumpers might not be as advantageous because they will cushion the impact you will have when playing defense against another robot. They will reduce the force with which you strike.

My team's robot is primarily a defensive/corner goal scoring robot. We chose not to use bumpers this year. Because of F = ma, it appears that this was a good decision. If we had used bumpers, our impact against other robots would have been smaller.

Now the question is, would the weight advantage of the bumpers have overcome the loss of acceleration due to the padding?

-- Jaine

Re: Bumpers: why not?
 

While there is much to be said for the impusle of hitting another robot in pushing them that is a dangerous manuver to rely heavily on. Refs are more leniant with bumper rots and ramming but penalties still do occure. In my case 1549's bot was able to push just about anyone sideways in addition to the impulse of initial contact. The bumpers do very little to decrease the a in F=ma. They offer enough shock absorbancy, however, to prevent robot damage.

Re: Bumpers: why not?
 

While your concept is worrect, I find it hard to believe that bumpers slow a robot down at all at impact. Unlike braking a car, bumpers are like putting a big, well...bumper, in front of the car. The bumpers are really to protect the frame of the robot from damage, not to make less force.

In fact, bumpers will actually increase force, as they add more mass (15 pounds) to the robot. Comparing a 120 lb robot to a 135 lb robot, the 135 lb robot has 12.5% more mass, and thus 12.5% more force. Even if bumpers did make accelleration slower, the added inertia of the 135 lb robot would cancel this out.

I encourage every robot to put bumpers on if they can, because without them, more penalties will be called on you, and your robot will get more damaged.

Re: Bumpers: why not?
 

update 15 states

so if your robot doesn't go into the corner goal normally but another robot pushes you into it, it is penalty for the other team. not you.

So were the referees calling this penalty wrong at a lot of places? This update may become handy to carry around in your manual binder if you think a referee ruled incorrectly at regionals.

Re: Bumpers: why not?
 

The big fault i'm seeing with this argument that more weight equals more force is that everyone's talking about ramming other robots, which is where this would apply.

For various reason's, my teams robot was (one regional, and that's all :( ) a rather good pusher. We did not however go racing across the field to ram the opponent. We generally had to maneuver to push the side of the opponents too. Our toughest opponents, if pushed from behind, would end up on the ramp and still able to shoot. Not to mention we did spend most of our time in the "personal" space of our opponents (so less distance ramming).

When going to the side to push, your weight affects the force of collision much less because of less speed. What matters is your pushing power, torque. The weight will and does increase torque.

Our robot had bumpers on 3 sides (ball collector, rarely used, on the front). My innate logic thinking says that this made us a more effective pusher when it came to getting that initial push from the side. We never sustained any damage (well a few dents in the shooter which was flush with the front of our robot) or penalties.

None the less, we couldn't push everyone (especially treads, which rather dominated the finals...). And I'm not doing so well in AP Physics this semester, so I could very well be wrong with some of the physics :confused:

Re: Bumpers: why not?
 

Well Our bot doesnt have bumpers for one simple reason. We ran outta time.

Re: Bumpers: why not?
 

Ours does because, well, why not? On one side we didn't have any, for ramp purposes. (Although I think it wouldn't have changed it much, it seems like it'd be sort of hard for a couple of pool noodles covered in smooth cloth to keep a high power, high traction, 6 wheel drive with good ground clearance off the ramp.) The other sides had them, except a small opening for ball collection. And, believe you me, we'd have been in sorry shape after the elims without them. However, Sparky didn't have them, and from what I saw, their frame still seemed to be in fine shape at the end of VCU. (I could be wrong, it's not like I examined it) As for them reducing defensive ability, If you were at VCU and watched us play, you might have noticed that we played almost entirely defense (yet at the beginning of Saturday we had the 4th highest avg match score, go figure :confused: ) we never felt that they were hurting us. Collision physics aside, that 15 lbs (Ours were about 10) gives you a good bit more traction, and in a pushing match against a similar drivetrain, this'll make the difference, not how hard your (illegal) high speed ramming is.

Re: Bumpers: why not?
 

The penalty is applicable to both robots. The bot attempting to score in the corner goal still is expected to have been built so it will not enter the goal.

Re: Bumpers: why not?
 

I think we had an instance of this in St. Louis during the eliminations. Both robots were DQ'd so the effect was a replay (tie). See my post in an earlier thread.

Re: Bumpers: why not?
 

No bumpers here, but simply because we lacked time, and our design didn't allow for it. Our frame itself would have made bumpers difficult, it's an octagon. Even had we put bumpers on it, there would be the problem of climbing the ramp, which we definately want to do. Also, bumpers reduce impact, but as a defensive robot, we're not worried about impacts to our bot. Hopefully, if our strategy pans out, we'll be one of the reasons why other teams have bumpers, yet we won't need them ourselves.

However, I love the bumper rule. I think it's a great addition to FIRST and it's strategy. Had our team chosen an offensive strategy this year, bumpers would have been a must. They're just too good to pass up, unless you're planning on being a reason for having them. :D

Re: Bumpers: why not?
 

I know bumpers played a key role in our win at GLR because we needed them for defense. They didn't hinder us getting up the ramp, and they protected us. We never got any ramming penaltys to my knowledge...but I could be wrong. They really didn't hinder us getting up the ramp. I wonder why some do and some don't? Is it simply placement, or material, or just design in general?

Re: Bumpers: why not?
 

we quite simply do not have the money to and we don't have the time. it would be better but we'll see in two weeks at the colorado regionals

Re: Bumpers: why not?
 

The reason that bumpers would have interfered with the ramp on our robot is because of how far into the chassis the wheels are set. The way we designed it, our robot needs quite a bit of clearance to climb the ramp, and bumpers just weren't going to allow for that.

Re: Bumpers: why not?
 

we fabricated bumpers for our robot for our second regional (waterloo) as we need the 15lbs down low... we have a fairly stable robot but it still helps. We still think were able to make it up the ramp (theoretically we will at least;))

Re: Bumpers: why not?
 

We were shoved into the corner goal at the BMR well past 3 inches, and no penalty was incurred. Has this been called at other regionals? We should know before we head off to W. Mich....

Re: Bumpers: why not?
 

bumpers are a good thing. 815 used bumpers. it allowed us to be the defensive giant we are without getting a penalty called on us. our defense tok us from 58th place at GLR allt he way to 2nd place in the finals. so in my opinon bumpers are a extremely good thing. they not only cut down on penaltys and damage to your robot

Re: Bumpers: why not?
 

yes 815 got called at GLR and we got disqualifyed and we didnt get the win counted to our record so. i believe the same head ref at GLR will be at western michigan

Re: Bumpers: why not?
 

In any given robot robot collision really only one team needs to have a bumper in place.

We had bumpers but never saw the need to add them. The robot was solid and it would have changed the ramp climbing ability.

I don't believe a single Ramming penalty was called at the PNW (but I may be mistaken)